Near Field Communication (NFC) is a standards-based connectivity technology that establishes wireless connection between two devices in close proximity of each other, typically in the order of a few centimeters. NFC allows users to transfer information by touching, or tapping, one device with another device. As with proximity card technology, NFC uses magnetic induction between two loop antennas located within two NFC-enabled devices that are in close proximity of each other, effectively forming an air-core transformer.
The act of bringing one NFC-enabled device to close proximity of another NFC-enabled device with or without the two devices physically contacting each other, referred to as an “NFC tap” or “one tap” operation hereinafter. With an NFC tap operation, a user can conveniently perform a variety of tasks, including mobile payment, secure login, wireless pairing, triggering peer-to-peer data exchange, file transfer, file sharing, mobile gaming, user identification, and so on. For example, by tapping an NFC-enabled computing device, such as a notebook computer or a desktop computer, with an NFC-enabled smartphone, information exchange between the laptop and the smartphone can take place while the two devices remain in close proximity, e.g., within 4 centimeters and theoretically up to 20 centimeters. In the United States, for instance, many smartphones currently on the market already contain embedded NFC chips that can send encrypted data a short distance to a reader located next to a retail cash register.
Presently, for an NFC tap operation to be carried out, both the tapping device and the tapped device need to be powered on and in an active state, e.g., not in a sleeping state. Take the above-mentioned NFC-enabled smartphone and NFC-enabled notebook computer as an example. When the lid of the notebook computer is closed, the notebook computer is typically in a state other than the Advanced Configuration and Power Interface (ACPI) S0 state. In other words, the notebook is in an active or working state. When the lid of the notebook computer is closed, a user may need to open the notebook computer's lid to “wake” it up by placing it in the ACPI state S0 in order for the notebook computer to interact with the smartphone based on the NFC technology.
An NFC-enabled notebook computer may be enabled for Always On Always Connected (AOAC). Such AOAC notebook computer may enter into a sleeping or non-active state when not being used, e.g., after being idle for a certain period, to conserve energy. However, even when the AOAC notebook computer is in the sleeping or other non-active state, the AOAC notebook computer still needs to wake up periodically to scan for application processes. The periodic waking of the AOAC notebook computer typically involves a real-time communication timer to allow applications to synchronize. This would introduce system complexity pertaining to system thermal management (especially if the notebook computer is in a bag), impact on battery life due to longer periodic wakes, possible operation system crash due to frequent repeated wakes, etc.
Furthermore, a purpose of waking up an NFC-enabled device from a sleeping or other non-active state may be to allow one or more applications installed on the device to synchronize with a server or another device. However, network connectivity during the time when the NFC-enabled device is in an active state may not be guaranteed. In other words, waking the NFC-enabled device may still result in unsuccessful synchronization.
The Detailed Description is described with reference to accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.